Chemisorption of alkyl thiols and S-alkyl thiosulfates on Pt(111) and polycrystalline platinum surfaces

The self-assembled monolayers prepared from 1-dodecanethiol (C12SH) or S-dodecylthio sulfate (Bunte salt, C12SSO3Na) have been characterised on polycrystalline gold and platinum surfaces and on Pt(111). Contact angle and impedance measurements show that the film quality decreases in the order Au/C12SH > Pt/C12SH similar to Au/C12SSO3-Na > Pt/C12S SO3Na. XPS measurements show that the S-SO3 bond of organic thiosulfates is broken on platinum surfaces and the state of the surface-bound sulfur is indistinguishable from that of thiolate. On platinum three sulfur species are formed upon SAM formation and we suggest that the catalytic activity of platinum is responsible for their existence in pristine monolayers. (c) 2005 Elsevier B.V. All rights reserved

Photoelectron spectroscopy study of irradiation damage and metal-sulfur bonds of thiol on silver and copper surfaces

Self-assembled l-dodecanethiol monolayers (SAMs) on silver and copper surfaces have been characterized with X-ray photoelectron spectroscopy (XPS) using both the synchrotron radiation and conventional Mg Kalpha excitation. Irradiation-induced changes in thiolate SAMs on Cu and Ag were observed. The identification of the sulfur species has been done. Results obtained confirm earlier studies of n-alkanethiols on silver. On copper (C12S/Cu), the observed S 2p spectrum is quite broad but the use of different excitation energies enabled us to identify four sulfur species on the surface. A S 2P(3/2) component of copper thiolate is observed at 162.6 eV. Three more doublets (161.9 eV, 163.2 eV and 163.8 eV) have been observed to develop during irradiation and they are assigned to chemisorbed sulfur on copper, to different dialkylsulfides and to sulfur-sulfur bonding, (C) 2004 Elsevier B.V. All rights reserved

Resonant inelastic x-ray scattering (RIXS) spectra of magnesium diboride

Using the tight-binding linear muffin-tin orbitals method, the soft x-ray fluorescence K-emission spectra of boron in MgB_2, excited close to the absorption edge, are estimated. In the calculations the angle of incidence between the direction of the incoming photon and the hexagonal axis of the specimen is 60 degrees and 75 degrees. Comparison with experiment is possible in the former case where good agreement is found. Furthermore, another resonant feature below the Fermi energy is predicted for the larger angle. This feature can be related to the excitations to the antibonding B pi-band in the neighbourhood of the L-H line in the Brillouin zone.Comment: 4 pages with 4 figure

Gene expression profiling for monitoring graft rejection in heart transplant recipients

Outcomes[Abstract] Heart transplantation is a life-prolonging therapy for many patients with stage D heart failure and other forms of advanced heart disease. However, graft rejection and/or immunosuppression-related side effects are major causes of morbidity and death among heart transplant patients. Graft rejection monitoring remains a challenge. It would be desirable to be able to detect rejection early enough and specifically enough to prevent allograft dysfunction without unnecessary overimmunosuppression. Hitherto, the main technique employed in monitoring the rejection status of a transplanted heart has been endomyocardial biopsy (EMB), which allows rejection to be screened for and monitored on the basis of the extent and distribution of lymphocytic infiltrates and associated myocardial damage. However, EMB has significant limitations: it is invasive, its sensitivity is limited by sampling efficacy, and it suffers from considerable between-observer variability. Although many noninvasive techniques have been investigated, none so far has proved able to match the performance of EMB. Currently, a multiparametric approach is employed that comprises clinical examination for signs or symptoms of heart failure, EMBs, drug level monitoring, allograft function tests (mainly echocardiographic studies), and screening for allograft vasculopathy. Gene expression profiling may be a promising tool for this purpose

Disentangling the determinants of symbiotic species richness in native and invasive gammarids (Crustacea, Amphipoda) of the Baltic region

Dispersal of alien species is a global problem threatening native biodiversity. Co-introduction of nonnative parasites and pathogens adds to the severity of this threat, but this indirect impact has received less attention. To shed light on the key factors determining the richness of microorganisms in native and invasive host species, we compared symbiotic (parasitic and epibiotic) communities of gammarids across different habitats and localities along the Baltic coast of Poland. Seven gammarid species, two native and five invasive, were sampled from 16 freshwater and brackish localities. Sixty symbiotic species of microorganisms of nine phyla were identified. This taxonomically diverse species assemblage of symbionts allowed us to assess the effect of host translocation and regional ecological determinants driving assembly richness in the gammarid hosts. Our results revealed that (i) the current assemblages of symbionts of gammarid hosts in the Baltic region are formed by native and co-introduced species; (ii) species richness of the symbiotic community was higher in the native Gammarus pulex than in the invasive hosts, probably reflecting a process of species loss by invasive gammarids in the new area and the distinct habitat conditions occupied by G. pulex and invasive hosts; (iii) both host species and locality were key drivers shaping assembly composition of symbionts, whereas habitat condition (freshwater versus brackish) was a stronger determinant of communities than geographic distance; (iv) the dispersion patterns of the individual species richness of symbiotic communities were best described by Poisson distributions; in the case of an invasive host, the dispersion of the rich species diversity may switch to a right-skewed negative binomial distribution, suggesting a host-mediated regulation process. We believe this is the first analysis of the symbiotic species richness in native and invasive gammarid hosts in European waters based on original field data and a broad range of taxonomic groups including Microsporidia, Choanozoa, Ciliophora, Apicomplexa, Platyhelminthes, Nematoda, Nematomorha, Acanthocephala and Rotifera, to document the patterns of species composition and distributio

The HL-60 human promyelocytic cell line constitutes an effective in vitro model for evaluating toxicity, oxidative stress and necrosis/apoptosis after exposure to black carbon particles and 2.45 GHz radio frequency

The cellular and molecular mechanisms by which atmospheric pollution from particulate matter and/or electromagnetic fields (EMFs) may prove harmful to human health have not been extensively researched. We analyzed whether the combined action of EMFs and black carbon (BC) particles induced cell damage and a pro-apoptotic response in the HL-60 promyelocytic cell line when exposed to 2.45 GHz radio frequency (RF) radiation in a gigahertz transverse electromagnetic (GTEM) chamber at sub-thermal specific absorption rate (SAR) levels. RF and BC induced moderately significant levels of cell damage in the first 8 or 24 h for all exposure times/doses and much greater damage after 48 h irradiation and the higher dose of BC. We observed a clear antiproliferative effect that increased with RF exposure time and BC dose. Oxidative stress or ROS production increased with time (24 or 48 h of radiation), BC dose and the combination of both. Significant differences between the proportion of damaged and healthy cells were observed in all groups. Both radiation and BC participated separately and jointly in triggering necrosis and apoptosis in a programmed way. Oxidative-antioxidant action activated mitochondrial anti-apoptotic BCL2a gene expression after 24 h irradiation and exposure to BC. After irradiation of the cells for 48 h, expression of FASR cell death receptors was activated, precipitating the onset of pro-apoptotic phenomena and expression and intracellular activity of caspase-3 in the mitochondrial pathways, all of which can lead to cell death. Our results indicate that the interaction between BC and RF modifies the immune response in the human promyelocytic cell line and that these cells had two fates mediated by different pathways: necrosis and mitochondria-caspase dependent apoptosis. The findings may be important in regard to antimicrobial, inflammatory and autoimmune responses in humansS

The Present and the Future of Degradable Dendrimers and Derivatives in Theranostics

Interest in dendrimer-based nanomedicines has been growing recently, as it is possible to precisely manipulate the molecular weight, chemical composition, and surface functionality of dendrimers, tuning their properties according to the desired biomedical application. However, one important concern about dendrimer-based therapeutics remains-the nondegradability under physiological conditions of the most commonly used dendrimers. Therefore, biodegradable dendrimers represent an attractive class of nanomaterials, since they present advantages over conventional nondegradable dendrimers regarding the release of the loaded molecules and the prevention of bioaccumulation of synthetic materials and subsequent cytotoxicity. Here, we present an overview of the state-of-the-art of the design of biodegradable dendritic structures, with particular focus on the hurdles regarding the use of these as vectors of drugs and nucleic acids, as well as macromolecular contrast agents.The authors would like to acknowledge the FEDER funds through the Programa Operacional Factores de Competitividade − COMPETE and the Portuguese funds through FCT − Fundação para a Ciência e a Tecnologia (PTDC/CTM-NAN/112428/2009, PEst/SAU/LA0002/2013 and PEst-OE/QUI/UI0674/2013-2014) that supported this work. V. Leiro is supported by FCT (SFRH/BPD/69110/2010)

Transaxillary implantation of the Impella CP mechanical circulatory support device as a bridge to heart transplant: first experience in Spain

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Diagnóstico y tratamiento de la obstrucción al flujo en dispositivos de asistencia ventricular de flujo continuo; un problema infrecuente

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¿La distrofinopatía de Becker es una contraindicación para el trasplante cardiaco?: experiencia de un centro

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